CN1960789B - Separation trays for distillation columns - Google Patents

Abstract

The invention relates to a separation tray (23) for a distillation column (1) of polymerizable substances, comprising at least one base plate (29) having a plurality of holes (30) and at least one attachment (31), characterized in that the attachment (31) divides the plurality of holes (30) into groups (32), wherein the attachment (31) forms an opening (33) through which a liquid can pass.

Description

Separation trays for distillation columns

technical field

The present invention relates to a separation tray of a distillation column for a polymerizable substance, a method for producing the polymerizable substance, uses of the polymerizable substance obtainable by the above method, and chemical products based on the polymerizable substance.

Background technique

All monomers used in free radical polymerization are generally considered as polymerizable substances, including methacrylic acid, acrylic acid, styrene or alpha-methylstyrene, especially methacrylic acid or acrylic acid, hereinafter collectively referred to as (meth)acrylic acid , among which acrylic acid is particularly preferably considered.

The purity standards for the monomers used to carry out large-scale polymerizations are becoming higher and higher, as are the requirements for the purity of bulk plastics. This is especially true for polymers used in the medical or hygiene fields. Polymers that absorb water or aqueous liquids, commonly referred to as "superabsorbents", are important components of many products in the medical or hygiene fields. Superabsorbents are mainly used in diapers, feminine hygiene products and incontinence products. Superabsorbents and other man-made materials are often obtained by free-radical polymerization of monomers with double bonds. Therefore, such monomers with double bonds such as (meth)acrylic acid are chemically very active substances, and they are prone to spontaneous radical polymerization when heated.

Distillation has proven to be a suitable processing method for obtaining high purity on a large scale. However, due to the heat of the monomers to be purified during the distillation, these monomers are prone to undesired polymerization. At this time, despite the addition of inhibitors, due to the overheating and long residence time of the monomers, at first, aggregated nuclei will mainly be formed in the dead zone, and these aggregated nuclei will grow over time and lead to more and more Undesirable polymers are formed, stop the distillation operation and cause troublesome cleaning of the distillation equipment, which is very expensive and places a heavy burden on people and the environment.

A distillation column is known, for example, from WO 00/53561. Although this document discloses the use of "double flow bottom" as the bottom plate of the column, which should be able to improve the separation efficiency, it does not disclose measures that can be used to overcome the above-mentioned shortcomings.

Contents of the invention

In principle, the object of the invention is to overcome the disadvantages caused by the prior art.

In particular, the object of the present invention is to prolong the time intervals for maintaining such distillation columns, wherein, preferably, the downtimes are also significantly reduced.

A further object is to achieve the highest possible purity during the course of the distillation process by means of a plurality of separation trays, with exactly repeatable and/or predetermined chemical processes taking place in each separation stage.

It is a further object of the present invention to provide uniform distribution of liquid or gaseous polymerizable species within a separation stage without formation of polymer deposits.

The above objects are achieved by the separation chassis, method, application and product according to the present invention.

The separation tray of the distillation column for polymerizable substances according to the invention comprises at least one bottom plate with a plurality of holes and at least one attachment which divides the plurality of holes into groups, wherein openings through which fluid can flow are formed with the at least one attachment .

The bottom plate preferably consists of a metal material, but other heat-resistant and acid-resistant materials can also be used. The outer shape of the bottom plate is selected taking into account the shape of the distillation column, so that the bottom plate can have, for example, a round, rectangular, square or similar shape. The base plate is provided with a plurality of holes, the purpose of which is in particular to enable liquid and/or gas exchange through the base plate. Where the pores are preferably large enough to trap liquid substances, and even preferably to form a bubble layer for heat exchange and component exchange between liquid and gaseous substances, the arrangement of the pores relative to the bottom plate can in principle be chosen arbitrarily and should be compatible with the interior of the column conditions are consistent. Thus, for example, the holes can be evenly distributed over the entire base plate, but it may also be necessary to use a different base plate structure, for example if the edge region of the base plate is required for positioning in the tower. Similarly, for example, if the base plate has to be supported on one side due to its spatial extent and the supports can close the holes. It is advantageous in this case that no holes are provided in these regions of the base plate.

It is now proposed that the attachment divides the plurality of holes into groups, wherein at least one attachment forms an opening through which the fluid can flow, the most important function of this attachment is to control the movement of the liquid accumulated on the base plate, so that on the one hand high The flow rate, but on the other hand does not form a "dead zone" in which the liquid stays for a relatively long time.

Particularly high flow velocities can occur, for example, if the gaseous substances passing through the base plate are not introduced completely uniformly over the base plate cross-section, but instead form a particularly strong source in certain regions. This makes liquid waveform excitation possible. In order to prevent this wave front from spreading across the entire base plate, resulting in different liquid levels on the base plate, the attachment acts as a kind of wave breaker by smoothing the vibrations of the upper liquid and bubble layer.

However, spatially strictly separating the bottom plate into different blocks does not necessarily guarantee better flow performance of the fluid, but by dividing it may form groups of holes that are less exposed to polymerizable substances, so that different distillations can be obtained for each block. Rate. For this reason, it is proposed that although the freedom of movement of the liquid is restricted by the attachment, the holes of the other blocks, in particular all holes, are accessible without restriction. This makes it possible to still form an opening through which fluid can flow by means of the attachment. These openings ensure that fluid can flow advantageously to each hole in the base plate.

The shape of the openings here should also be selected taking into account the liquid, the polymerizable substance, the column or its operation, eg circular openings, rectangular openings, grooves etc. mentioned here. It should also be clear here that the opening can be completely or partially defined or formed by the appendage. In principle, with regard to the arrangement of such openings, it is advantageous if the openings are arranged in the lower part, for example in the vicinity of the floor. This ensures, on the one hand, that the propagation of the wave motion of the upper liquid or fluid layer is interrupted, while deeper layers in the vicinity of different hole groups can communicate with each other. It should be noted here that the openings are designed in such a way that as few as possible, preferably no dead spaces are formed, where dead spaces are areas in which the fluid stays for a relatively long time.

Liquids tend to aggregate in such dead spaces, which can lead to at least partial clogging of the pores in the long run. As a result, gas or liquid exchange takes place through only a small number of pores, at which point the increasing gas pressure leads to an additional excitation of the liquid. As the substance aggregates more and more, the distillation process can no longer be performed in the desired quality, so cleaning and maintenance measures are required. This in turn causes the distillation process to have to be interrupted and the column to be shut down. The separation chassis must be re-cleaned in a complicated way and then reinstalled, and this complicated measure can be delayed at least for a longer time with the accessories on the chassis recommended here. Cleaning can also be done faster since polymer deposits occur in far fewer places. This means that, on the one hand, the distillation column can be operated for a longer period of time and provide the desired distillation result, and on the other hand, the cleaning procedure can also be carried out faster, thereby reducing the downtime of the distillation column.

According to an advantageous development of the separating chassis, the opening extends from the base plate over a height in the range of 1 mm to 100 mm, preferably 5 mm to 50 mm, particularly preferably 10 mm to 30 mm. This means, in particular, that the opening is only partially defined by the appendage. In this case the opening is also at least partially delimited by the base plate. Here the opening can be defined solely by the base plate and the attachment, but also by other components together. Here the height of the opening is selected such that the fluid can move or flow relatively unhindered in the vicinity of the base, so that a uniform flow of liquid or fluid to the holes is ensured, while the liquid and/or fluid layer remote from the base is penetrated by the attachment.

According to a preferred embodiment, at least one attachment comprises at least one straight rib. An attachment of this design should be selected in particular if the base plate likewise has straight edges, that is to say in particular rectangular or square. This makes it possible to divide the holes on the base plate into groups of almost equal number in a simple manner. However, it is also sometimes required that the attachments, in addition to the straight ribs or sections, also include curved guide surfaces, which induce the existing fluid to flow in such a way that dead zones are avoided in the vicinity of the attachments, the orientation of the ribs relative to the base can in principle be Arbitrary choice. This also means that the straight ribs can extend over the entire base or only over partial areas of the base.

It is in this case that it is advantageous for the accessory to have at least one of the following configurations:

(a) Multiple attachments are provided with a rib;

(b) An attachment is provided with a plurality of preferably interconnected ribs.

This means in particular that the attachment can be designed as a component with a plurality of different or identical ribs, but on the other hand it is also suitable for producing a single-part attachment or a composite system from a plurality of ribs which are connected to each other, in particular by joining technology. In such composite systems, the ribs are detachable or connected to one another by material bonding. As a decisive criterion for both configurations, it is conceivable, for example, that a plurality of attachments each comprising a rib contact each other only via the base plate and/or other components of the tower, whereas in the case of more complex one-piece attachments and/or interconnections in the The ribs that together form an accessory form a direct connection or bond through the components of the rib and/or the component parts of the accessory themselves. Variant (a) allows the ribs to be arranged relative to each other very flexibly, while configuration (b) has the advantage that it can be assembled simply and takes less time. From these points of view, a complex appendage formed by several ribs is used in the central area, while in the edge area, depending on the shape and/or shape of the appendage or tower, additional individual ribs are provided to complete the first appendage , which is advantageous, whereby it can be ensured, for example, that groups of holes with substantially the same number are formed.

According to an advantageous development, at least one rib has a length, wherein the openings are at least partially bounded by at least one of the following elements:

(a) at least one rung which is part of the tendon;

(b) at least one spacer which is a separate part;

Where the element has a width, the sum of the element widths is less than 80%, preferably less than 60%, in particular less than 40%, of the length of the rib. In addition to the possibility of attaching the attachment to the tower and/or vessel at a distance from the base, a structural unit with a base that can be easily mounted is preferably recommended here. This means, in particular, that the base plate and at least one accessory can be inserted together into the tower, so that the at least one accessory should itself be fastened to the base plate. It is now proposed here that this is achieved by crosspieces or spacers or both elements.

The rungs which themselves form part of the ribs can for example be manufactured by forming methods such as casting, milling or the like. The crosspieces therefore consist of the same material as the ribs themselves. However, it is advantageous if the crosspieces and the ribs themselves are made of different materials, where, for example, the ribs are first made in one piece and then the crosspieces are connected (detachable or non-detachable) to the ribs using joining techniques.

Alternatively or in combination, separate spacers may be provided on the base plate, the spacers themselves comprising means for securing the ribs. This has the advantage that, for example, the ribs can be made substantially rectangular, wherein openings of the desired height can be formed by means of spacers of different configurations, which leads to an economical manufacture of the ribs on the one hand and, on the other hand, a convenient and process-dependent adjust the opening.

The crosspieces and/or spacers are used in particular to stabilize and/or position the ribs relative to the base, i.e. the ribs are arranged, for example, in the edge regions of the base by means of the crosspieces and/or spacers, respectively, and in the central region according to The difference in the length of the ribs provides an additional element (rails and/or spacers). They preferably extend all the way to the floor, but the crosspieces can also be made shorter in order to form a certain contour of the opening, which has a favorable influence, for example, on the flow behavior of the liquid.

As mentioned above, it is particularly advantageous if the sum of the widths of the crosspieces and/or spacers is less than 80%, in particular less than 60%, particularly preferably less than 40%, of the length of the ribs, so as few and preferably narrower elements as possible are preferably used to stabilize the tendons. This ensures that the flow of fluid in the vicinity of the base plate can expand relatively unimpeded. It is advantageous here to design the crosspieces and/or spacers with a flow-favorable contour, in particular to form a suitable flow-around edge (for example a circular cross-sectional shape). Depending on the flow velocity occurring, a greater number of crosspieces and/or spacers may be required, but they are made thinner, whereas in other applications a crosspiece and/or spacer each in the edge area of the base plate is sufficient. Sufficient, but no rungs and/or spacers in the center area. For the sake of clarity, it should be clear here that the length of the rib is described as the maximum extension length in one direction, and the width of the crosspiece and/or spacer should be determined along the same direction, where the width and length should be able to lie in the same plane or in planes parallel to each other.

According to yet another configuration, the split chassis is made such that at least one attachment divides the bottom plate into a plurality of blocks each with a set of holes, wherein each block preferably comprises between 1.2 m ² and 0.3 m ² , preferably between 1.0 m ² and 0.5 m 2 . m ² , especially an area in the range of 0.8 m ² to 0.6 m ² . In principle such a separate chassis with a one-piece or multi-part base can be formed from a plurality of individual bases, wherein in principle it is ensured that an unevenness of the base of less than 3 mm/m, in particular less than 2 mm/m, preferably less than 1 mm/m is achieved Spend. The circular base preferably has a total diameter in the range of 2 m to 7 m, in particular 3 m to 5 m. The holes on the base plate here preferably have a diameter of 15 mm to 40 mm, in particular 20 mm to 30 mm, and it is further proposed that the separating chassis has a cover plate, wherein the cover plate is preferably arranged at a distance from the base plate of 60 mm to 200 mm, especially 80 mm to 150 mm, particularly preferably At a distance in the range of 100 mm to 120 mm and in particular likewise with a plurality of holes.

The cover plate has several different functions. One function, for example, is to prevent or at least significantly reduce in this way rising gaseous substances which partly carry away liquid substances accumulated on the bottom plate. In this way, the separated liquid deposited on the cover plate as the gaseous mass rises is redistributed evenly and fed back to the bottom plate below the cover plate. In order to enhance this effect, the cover plate has a plurality of holes, which are not distributed parallel to the preferred flow direction of the gaseous substance, but are inclined relative to this flow direction, for example at an angle between 10° and 50°, whereby it is possible to Bring the substance into intensive contact with the cover plate. These advantageous effects lead individually or in combination with each other to an increase in the efficiency of the separation chassis. In addition, the cover plate can facilitate at least a mass or heat exchange, whereby the separation efficiency is further increased and at the same time a uniform flow of the gaseous substances from the separation tray that has just passed through to the next separation tray is possible. The cover plate thus acts as a flow distributor, which ensures a uniform inflow to the next separation tray. The cover plate can therefore be designed similarly to the base plate as a flow distributor with a grid structure or honeycomb structure or perforated plate. When designing the cover plate structure as a honeycomb structure from a plurality of plies forming the through-flow openings, the cover plate has a thickness of at least 50 mm, preferably at least 100 mm, in particular 150 mm, but particularly preferably not more than 300 mm.

According to an advantageous development of the separating chassis, the separating chassis comprises a support element comprising at least one solid abutment, which is in contact with a side of the base plate facing away from the at least one accessory, preferably at least within 200 mm to 1000 mm, in particular 350 mm to 800 mm, particularly preferably in the range of 400 mm to 600 mm. It is also possible here that the supports are at least partially arranged substantially perpendicular to one another and optionally connected to one another by connecting elements, wherein the supports can have mutually different dimensions in different directions.

The support can have multiple functions, wherein here in particular at least one of the following two functions is particularly important: to fix the separation chassis relative to the tower or other separation chassis, and/or to increase the rigidity of the separation chassis, if the support If a piece is used for fastening, then the support is preferably arranged to extend as far as the edge region of the separating chassis, so that it can be connected to elements of adjacent components (for example towers or other separating chassis). The function of increasing the rigidity of the separating chassis is particularly important if the separating chassis or all base plates span an area of greater than 10 m ² , preferably greater than 13 m ² , particularly preferably greater than 15 m ² . By using supports to ensure that the base plate remains flat and avoid sinking of the base plate in the central area relative to the edge areas when the separating base plate becomes larger and larger, this unevenness of the base plate leads to the formation of a boundary layer near the base plate, which makes The tendency to flow is reduced and therefore tends to polymerize, and because of the relatively large area of this unevenness, very many pores will be blocked due to polymer deposition. This process of limiting the working capacity of the distillation column can be solved by using the supports recommended here. to avoid.

In this context, it should be noted that a solid support is to be understood as meaning in particular a support which has no cavities inside it, i.e. the space is completely surrounded by the support material, which contains no inclusions or pores caused by manufacturing, preferably , the support is not designed in such a way that although it is very rigid, it is still provided with a cavity-forming profile. Although in principle such supports can be produced from U-shaped profiles with thinner walls, solid supports with relatively thick walls are preferably recommended here. The support is attached to the side of the bottom plate facing away from the liquid surface. Therefore, the support is not used for direct flow control, but only sometimes as an outflow edge or outflow surface for fluids or liquids that pass through the bottom hole or that condense on the support or the separating pan.

According to another configuration, at least one support has at least one recess in the vicinity of the base plate, wherein the sum of the extension lengths of the recesses is at least 80% to 30%, in particular 70% to 40%, particularly preferably 60% to 46, of dimension 46. 55% range. The recesses here have the function of allowing gaseous substances to flow through, and sometimes represent the outer edge of the liquid stream that falls on the support. The larger the surface of such a seat, the more liquid is likely to accumulate there through the holes. Here too, therefore, there is a danger of forming a boundary layer, in which polymerization occurs rapidly. For this reason, it is proposed here that an edge is already formed after a short flow path, so that a further flow along the support is prevented due to gravity. These edges promote, for example, the formation of droplets, which break free from their supports and continue to fall freely in the direction of the bottom of the distillation column or the separation tray located in the middle. In order to ensure, on the one hand, this favorable dripping of the liquid, but on the other hand On the one hand, the performance of improving the rigidity of the support is ensured, and it is proposed that the sum of the extension lengths is within the above-mentioned dimensional percentage range. In this case, it should also be pointed out that the dimension should be determined along the direction of the longest extension of the support, wherein the extension length of the recess is determined along the same direction, so that the extension length and dimension are located on the same plane of the support or parallel to each other. in plane.

According to a further embodiment, the support is T-shaped, wherein at least one recess is provided on a part of the support which is substantially perpendicular to the base. The T-shaped structure has the advantage of providing a contact surface towards the base plate with the upper support part substantially parallel to the base plate, which ensures a flat, relatively large area of fit, thus giving sufficient possibility of connection to the base plate , it is advantageous in this respect that the base plate has no holes in the area where it abuts against the support. Furthermore, the substantially parallel support portion has the advantage that the first outer edge is already formed after the liquid has flowed a short distance, ie exactly where the upper support portion terminates. Here, the abutment part, which is arranged substantially perpendicular to the base, is so far away from the edge that liquid is prevented from accumulating in the collection area of the upper and lower abutment part due to surface tension.

However, it should be considered that the gaseous polymerizable substance may condense on the bottom surface of the support portion substantially parallel to the base plate, where there is now the possibility that these liquids flow down the support portion substantially perpendicular to the base plate. For this reason, it is proposed here to provide at least one recess. In addition, because this method can save materials and reduce manufacturing costs, and significantly reduce the weight of components and the labor intensity of installing such a separate chassis, it is advantageous to set the recess. These recesses are designed as is often done, where the point of structural lightness can be further strengthened by a suitable choice of materials.

According to an advantageous development of the split chassis, it is provided that at least one T-shaped support has a foot arranged parallel to the base plate with dimensions in the range of 50 mm to 100 mm, in particular 60 mm to 90 mm, particularly preferably in the range of 70 mm to 80 mm , wherein within a distance of less than 10 mm, in particular directly on the foot, at least one recess is provided, preferably having a width in the range of 40 mm to 120 mm, especially 60 mm to 100 mm and particularly preferably 75 mm to 85 mm. To produce such a support, it is also possible to connect a plurality of individual parts to one another detachably (for example with connecting elements) or non-detachably (for example by welding). The size selection of the T-shaped support is basically carried out under the consideration of two points: on the one hand, it should be noted that the support should sufficiently provide the desired rigidity of the separation chassis, and on the other hand, it must be considered that the heat capacity of such a support can The operation of the column plays an important role, which means that in the case of temperature fluctuations in the column interior, no excessive temperature difference must be allowed between the gas passing by and the support, because this would increase the condensation and/or aggregation of substances danger.

Furthermore, it is proposed that at least one support and at least one attachment are arranged perpendicular to one another. This means that the support and the at least one attachment form a truss structure which stabilizes the base plate in one plane, to a large extent also in the same way that the at least one attachment has a direct connection region to the base plate. The strengthening of the base plate by means of such a truss construction system leads to the fact that the above-mentioned area can be designed narrower with respect to the size and/or width of the T-shaped support, that is to say preferably in the lower half or lower third of the given value range. within one of the areas.

)，聚苯胺漆或 具有无金属离子表面的涂层(例如玻璃)或至少两种这些涂层的混合物作为涂层。如果使用玻璃作为涂层剂，那么优选采用由氧化硅(SiO₂)，氧化钙(CaO)，氧化钠(Na₂O)，有时带有较大量的氧化硼(B₂O₃)，氧化铝(Al₂O₃)，氧化铅(PbO)，氧化镁(MgO)，氧化钡(BaO)或氧化钾(K₂O)的冷却熔体得到的工业玻璃。优选地，这种工业玻璃包括重量百分数为至少50％，优选至少65％，极其优选至少80％的SiO₂。It is also proposed that the separating chassis is at least partially coated with a coating which has better sliding properties for liquids than steel. It should be noted here that this coating extends at least partially to the following elements: base plate, supports, accessories, spacers. In principle, the coating extends from the surface of the component for several microns to several millimeters (preferably 50 μm to 1000 μm, especially 100 μm to 800 μm, especially 200 μm to 400 μm), especially recommended polyfluorocarbons, especially polytetrafluoroethylene (Teflon

), polyaniline paint or a coating with a metal ion-free surface (eg glass) or a mixture of at least two of these coatings as coating. If glass is used as coating agent, it is preferred to use silicon oxide (SiO ₂ ), calcium oxide (CaO), sodium oxide (Na ₂ O), sometimes with larger amounts of boron oxide (B ₂ O ₃ ), aluminum oxide (Al ₂ O ₃ ), lead oxide (PbO), magnesium oxide (MgO), barium oxide (BaO) or potassium oxide (K ₂ O) cooling melt obtained industrial glass. Preferably, such industrial glass comprises SiO ₂ in a weight percentage of at least 50%, preferably at least 65%, very preferably at least 80%.

和塑料组成)来制造至少一个构件或整个分离底盘，由Teflon

或塑料制备的底板特别有利。In principle, the separating chassis can also be at least partially made of a non-metallic material, so that no separate coating of the above-mentioned type is required. In addition to the above materials, plastic or composite materials (such as Teflon

and plastic) to manufacture at least one component or the entire separate chassis, made of Teflon

A base plate made of plastic or plastic is particularly advantageous.

It is added that it is advantageous for the container to have a plurality of separating trays and to be provided with at least one spraying device which can be used to spray the bottom surface of the at least one separating tray with the polymerizable substance. This spray impact device effectively removes part of the polymerizable substances attached to the bottom surface of the separation chassis, thereby avoiding polymerization at these positions. Here, it is preferable to adopt such a structure, that is, the separation chassis at the bottom of the tower is positioned in the role of this spray device Within the range, it is advantageous here that the spraying device is supplied with a liquid polymerizable substance from the collection reservoir of the container and sprays the polymerizable substance evenly distributed onto the bottom surface of the separation chassis, the spraying device preferably has a plurality of nozzles, These nozzles form an evenly distributed spray area over the cross-section of the separating chassis. The injection device is very particularly preferably operated at high pressure, for example at a pressure in the range of 2 to 5 bar, preferably 3 bar. Secondly, the spraying device is preferably positioned at a short distance, preferably at most 1 m or 50 cm, from the underside of the separating chassis, wherein this distance can be varied taking account of the spraying area and/or the number of nozzles. The spraying device described above is preferably used in combination with a separating chassis of the type described here according to the invention. Additional details can be obtained from the description of the figures.

Furthermore, the invention relates to a method for the purification of polymerizable substances, wherein the polymerizable substances are conveyed into the column according to the invention as liquid substances via an inlet line and are at least partially converted into substances in the gaseous phase in the inner region, where the gaseous substances are preferably flow with isotropic density to the first separating tray arranged above the inlet pipe, when the maximum deviation from the mean value of the isotropic density in a plane between the inlet pipe and the first separating tray is at most 15%, if A maximum deviation of at most 10%, in particular only 5%, is particularly advantageous, where the plane is preferably closer to and parallel to the first separation chassis in order to ensure a relatively compact tower, wherein the plane In particular at most 100 mm below the first separating chassis, but the plane can also be at most 50 mm, or even at most only 10 mm, from the first separating chassis.

A particularly homogeneous distillation with a very low tendency to polymerize can be provided in the column if at least one separating tray is designed in such a way that an isotropic density also develops in the liquid phase of the polymerizable substance. This can be achieved in particular by using a so-called "double flow floor". In this way it is sometimes possible to achieve the recommended isotropic density flow of the gaseous phase above the separation chassis, which further significantly reduces the maximum deviations that occur.

In general, all chemical compounds known to those skilled in the art which tend to polymerize are considered polymerizable substances according to the invention. The polymerizable substance is preferably a monomer used in the manufacture of bulk plastics, such as styrene, alpha-methylstyrene, methyl methacrylate, butyl acrylate, and the like. Furthermore, the polymerizable substance employed in the process of the invention is preferably (meth)acrylic acid. The term "(meth)acrylic acid" refers here to both the compound having the technical name "acrylic acid" and the compound having the technical name "methacrylic acid", wherein acrylic acid is preferred of the two. Furthermore, in the process according to the invention an absolute pressure is preferred in the inner region. In the inner region of the column the pressure is preferably in the range of 50 to 400 hPa (hPa), especially 100 to 300 hPa, particularly preferably in the range of 150 to 250 hPa (where 1 hPa = 1 mbar = 10 ² Newton/square meter [N/m ² ] =10 ² Pa).

Furthermore, in the process of the invention the liquid substance is preferably superheated, in which case the temperature of the main constituents of the liquid substance - mainly polymerizable substances - is at least 1 °C higher than the boiling point of the main constituents of the pure liquid substance, Especially at least 5°C, particularly preferably at least 10°C.

Furthermore, the present invention relates to a method for producing a polymerizable substance, wherein the polymerizable substance is synthesized in a reactor from at least one educt, which is then subjected to the purification method according to the invention, the synthesis of the polymerizable substance is not limited to a specific method, but all methods known to professionals can be considered. In the synthesis of acrylic acid, in particular at least two stages of gas-phase oxidation, wherein preferably acrolein is obtained in a first step by catalytic oxidation of propene, and in a further step gas-phase acrylic acid is obtained, this gas phase is then combined with a liquid in a quench , especially water or an organic compound having a boiling point higher than water or a mixture thereof, and purified directly or indirectly according to the purification method of the present invention, details of the method for the manufacture and further purification of acrylic acid can be cited from WO 02/055469 and therein obtained from other references. They are cited here as part of this disclosure.

Furthermore, the invention relates to the use of the inlet pipe according to the invention for the distillation of polymerizable substances.

Secondly the invention relates to a polymerizable substance obtainable by the process according to the invention, wherein the polymerizable substance is especially acrylic acid or methacrylic acid, particularly preferably acrylic acid.

Furthermore the invention relates to a polymerizable substance according to the invention, especially acrylic acid, as a starting compound for use in molding materials (formmassen), fibers, films, absorbent polymers, polymers for leather and textile processing, for Applications in polymers for water treatment or polymers for soap making.

The invention also relates to molding materials, fibers, films, absorbent polymers, polymers for leather and textile processing, polymerizable materials for water treatment, at least partially based on the polymerizable substances according to the invention, especially acrylic acid-based substances or polymers used in soap making.

Description of drawings

The invention will now be described in detail with the aid of the drawing, in which the illustrated embodiments represent particularly preferred embodiments of the invention or of a combination of the invention with the known field of distillation columns. It should be pointed out here that the invention is not limited to the illustrated embodiment. In addition, further details about the technical field of distillation columns are presented.

The accompanying drawings indicate:

Figure 1 schematically represents the structure of a column with inlet pipes for polymerizable substances in a perspective view;

Fig. 2 is a schematic sectional view of a separate chassis structure;

Fig. 3 is the schematic diagram of another embodiment of separation chassis;

Fig. 4 is a schematic sectional view of another embodiment of the separation chassis;

Figure 5 is a simplified schematic diagram of different embodiments of a flow rectifier;

Figure 6 is a partial schematic view of one embodiment of a coated base plate of a split chassis;

Fig. 7 is a schematic diagram of acrylic acid manufacturing equipment;

Figure 8 schematically represents the structure of the test device used to determine the density distribution;

Figure 9 schematically represents the corrugated bottom plate of the separation chassis in a perspective view;

Fig. 10 schematically shows another embodiment of an inlet pipe with a flow mixer in a perspective view;

Figure 11 is a partial sectional view of a container with a spray device;

FIG. 12 is a top view of the spraying device shown in FIG. 11 .

Detailed ways

1 schematically shows in section a column 1 for distillation of polymerizable substances, wherein the column comprises a container 2 with a lower bottom 8 and an inlet 4 for the polymerizable substance, which leads into the inner region of the container 2 within 5. As will be explained in more detail below, the column 1 has various means for uniform distribution of the substance in the container 2 .

In order to be able to understand the flow process of the polymerizable substance in principle, its path through the column 1 is firstly explained. Usually the polymerizable substance exists initially in liquid form and is transformed or superheated into a vapor or gaseous state by means of a heater 27 from which the substance flows along the flow direction 25 into the inner region 5 of the container 2, where When entering the inner region 5 or shortly thereafter, the partially liquid and partially vaporous substances continue to flow to the separation tray 23 along the flow direction 25 (here indicated by an arrow vertically upward), and the first stage distillation is realized in the separation tray. The condensed components of the substance fall back in the form of droplets 26 in the direction opposite to the flow direction 25 onto the feed line 4 or onto the lower bottom 8 of the container 2 . The container 2 has a collection reservoir 24 at its deepest point, in which the condensate collects, and this collection reservoir is connected to a pump 28, which pumps the condensate in the collection reservoir 24 from the column 1 transport away.

When further observing the input pipe 4, at first it can be seen that the input pipe has an inlet 13 and an outlet 14, wherein the outlet 14 is arranged near the lower bottom 8 of the container 2 and substantially parallel to the lower bottom, and the input pipe 4 is represented as The separate component projects through the container 2 into the inner region 5 via a connection piece 3 . The inlet pipe 4 has straight and curved sections, wherein they are designed such that the outlet 14 is arranged with its central axis 19 concentrically to the central axis 62 of the container 2 . A flow controller 15 is arranged on the section 18 of the inlet line 4 which leads to the outlet 14 . The flow controller 15 includes a plurality of baffles 16 to ensure that the channels 17 allow a balanced flow of the polymerizable substance inside the inlet pipe 4 . A conical flow distributor 20 is disposed concentrically with the central axis 19 or central axis 62 with its tip 21 closest to the outlet 14 . As shown by the arrow (flow direction 25) in Fig. 1, the layout of the flow distributor 20 in the inner region 5 of the container 2 results in a deflection of the inflowing material, here in order to reserve, the container 8 is additionally designed in such a way that the flow guide surface 61 is conducive to the uniform distribution of substances in the container 2. Furthermore, the arrangement of the flow distributor 20 shown achieves the advantage that the inflowing substance does not immediately mix with the condensate stored in the collection reservoir 24, so that the flow distributor 20 also has a protective function here.

With regard to the inlet pipe 4, it should also be noted that it is equipped with a plurality of means for thermal insulation with respect to the inner area 5, wherein these means are arranged in a partition 9 which extends over the entire outer surface 6 of the inlet pipe 4, This outer surface is in contact with the inner region 5 of the container 2 . The inlet pipe 4 is designed as a double-walled pipe and thus has two outer sleeves 10 arranged coaxially with one another. A vacuum insulation layer 11 is formed between the two jackets 10, wherein the inner surface 12 of the jacket 10 is made as a mirror surface.

In order to prevent particularly liquid constituents of the polymerizable substance from accumulating or adhering to the surfaces delimiting the lumen 5, the entire outer surface 6 of the inlet tube 4, the entire outer surface and/or tip 21 of the flow distributor 20 and the inner wall of the container 2 Both have a coating 22 which has better sliding properties for fluids than steel.

FIG. 2 schematically shows in partial section a separation chassis 23 comprising a cover 41 , an attachment 31 , a base 29 and a support 44 , between which a liquid 60 is provided. The gaseous polymerizable substance comes into contact with the liquid 60 through the holes 30 in the base plate 29 in the direction of flow 25 , while a different boundary layer forms between the base plate 29 and the cover plate 41 . For example a liquid layer 56 substantially free of gas bubbles 59 can be seen, above which is a layer of vapor bubbles 57 or a layer of foam, which in effect represents a boundary layer between the liquid 60 and the gaseous volume. In addition, a layer of droplets 58 is arranged between the cover plate 41 and this vapor bubble layer 57, where the droplet layer is mainly characterized by the gaseous state of the substance to be distilled, mainly the droplets 26 from the cover plate 41 . Whereas gaseous substances move from bottom to top in flow direction 25 (as shown in the figure), liquid 60 falls to bottom 8 (not shown) in the opposite direction (counterflow principle) due to gravity 55 .

It should be added here that the cover plate 41 does not have to be made in one piece, but can also be made in multiple pieces, the cover plate 41 preferably comprising a plurality of structural plates and/or plastic elements, which are piled up in piles, And form a (preferably not linear) flow path between them. The plates and/or plastic elements are preferably arranged substantially parallel to the direction of gravity, in particular at a distance 42 from the bottom plate 29 in the range of 100 to 200 mm, and the plates and/or plastic elements are preferably prepared such that the cover plate 41 or stack The thickness is about 100 to 200 mm.

The base plate 29 has a plurality of holes 30 which are divided into groups 32 by means of attachments 31 (see FIG. 3 ). Attachment 31 is designed in such a way that fluid or liquid 60 is formed through openings 33, and they ensure that liquid passes through adjacently arranged holes 30 in arrow direction 54 (that is, substantially parallel to base plate 29 and/or substantially perpendicular to the direction of the substance). flow direction 25) for exchange. Here the attachment 31 is coated with a coating 22 which has better sliding properties for liquids than steel and at the same time the attachment 31 acts as a separation limit or support wall for the two plates 29 and 41, in this way securing the cover plate 41 It is arranged at a predetermined distance 42 from the bottom plate 29 , preferably parallel to the bottom plate 29 . Considering the size and/or height 34 of the openings 33, it can be seen that they are substantially designed slightly smaller than the liquid layer 56, so that the flow is hindered in the upper region of the liquid layer 56 close to the bubble layer 57, whereas Liquid can move relatively unimpeded along arrow 54 in the vicinity of bottom plate 29 . The cover plate 41 can also be designed as a flow rectifier 64 , in particular as a honeycomb structure 68 with a plurality of openings through which fluid can flow.

On a side 45 facing away from the attachment 31 a support 44 is provided as a support. The support 44 is T-shaped and has a foot 49 of imaginary dimension 50 arranged substantially parallel to the base plate 29 and a lower support part substantially perpendicular to the foot. Recesses 47 are provided on that part of the T-shaped support 44 that is substantially perpendicular to the base plate 29 . In the exemplary embodiment shown, the recesses 47 are arranged at a distance 51 of less than 3 mm. This creates a plurality of outer edges 63 which encourage falling fluid (indicated by dashed lines) to form droplets 26 and to fall off the surface in the direction of gravity 55 . In order to enhance this effect, both the bottom plate 29 and the support 44 are coated with, in particular, Teflon Coating 22.

FIG. 3 schematically shows a further embodiment of the separation chassis 23 according to the invention in a top view, which, as can be seen here, spans the entire inner region 5 of the column 1 or of the vessel 2 . However, it is also possible to place a plurality of preferably rectangular separating chassis 23 of this type in one platform, which then spans the entire inner area 5 of the column 1 and finally the entire inner area 5 of the column 1 . The separating chassis 23 shown here in the form of a circular design has a plurality of holes 30 , wherein these holes are divided into groups 32 by means of attachments 31 . The appendage 31 comprises a plurality of ribs 35 interconnected in a regular arrangement by joining techniques. The appendage 31 is designed to divide the base plate 29 into blocks 40 each having a group 32 of a set of holes 30 . The attachment 31 is designed here in such a way that the exchange of liquid or fluids of adjacent blocks 40 in the direction of the arrow 54 is still ensured. Furthermore, the support 44 on the underside 45 of the base plate 29 coated with the coating 22 is shown in dashed lines. Here the support 44 is directly connected to the tower 1 to enhance the stability of the base plate 29.

Figure 4 shows another cross-sectional view illustrating a modification of the separation chassis 23 of the present invention, as can be seen from Figure 4, the support 43 of the separation chassis 23 is provided with a support 44, which is connected to the container of the tower 1 by means of a protrusion 53 2, thereby ensuring a substantially horizontal positioning of the separation chassis 23 in the inner region 5 of the column 1, where the protrusion 53 has been shown simplified. In practice several adjustment possibilities can be provided so that the separating chassis 23 can be positioned precisely horizontally within the inner chamber 5 . The illustrated support 44 has a dimension 46 and is T-shaped. In addition to the support part which is arranged substantially perpendicularly to the base plate 29 , the support 44 also has a foot 49 which serves as a support plate for the base plate 29 . A plurality of recesses 47 are directly attached to the vertical support part at the foot 49 , wherein here the recesses are formed as a semicircle. The semicircular recess 47 is not necessary, but is advantageous in terms of rigidity due to its rounded contour. These recesses 47 can be described by an extension 48 measured substantially parallel to the base plate 29 and/or the foot 49 . The recesses 47 each have a width 52 in their vertical direction. Preferably, the recess 47 is designed such that the sum of the extensions 48 is at least in the range of 80% to 30%, preferably 70% to 40%, in particular 60% to 65%, of the dimension 46 .

In FIG. 4 , an appendage 31 in the form of a rib 35 is shown above the base plate 29 . The ribs 35 are fastened by means of spacers 38 in the edge region of the bottom plate 29 close to the container 2 . Merely by providing such a spacer 38 , a gap is already created between the rib 35 and the bottom plate 29 . This gap may have caused the beneficial effects on fluid flow described herein. However, a further specific embodiment of a rib 35 with a single crosspiece 37 is now also shown in FIG. 4 for the sake of clarity. The crosspieces 37 and/or the spacers 38 have a width 39 , wherein the sum of the widths 39 is significantly smaller than the length 36 of the ribs 35 (eg less than 50%). With regard to the above-mentioned percentages, it should also be pointed out that here preferably only those spacers 38 and crosspieces 37 with a width 39 which are in direct contact with the bottom plate 29 , ie virtually impede the flow over the entire liquid layer, are involved. Openings 33 are thus formed by means of crosspieces 37 or spacers 38 , which preferably have a height 34 from base plate 29 in the range of 1 mm to 100 mm, in particular 5 mm to 50 mm and particularly preferably 10 mm to 30 mm.

FIG. 5 schematically shows different embodiments of a flow straightener 64 for better flow of the vapor-shaped polymerizable substance to the separation chassis 23 . In principle, it should first be pointed out that such a flow rectifier 64 fulfills the function of achieving a uniform flow of the polymerizable substance to at least one separation chassis 23, uniform here meaning that at least one of the two factors of flow velocity and flow direction The cross-section of the inner region of the column 1 close to the separation tray 23 has a deviation of only less than 20%, in particular less than 10% and preferably less than 5%. This means, for example, that at a given flow velocity of vapor-like matter of 2 m/s to 5 m/s [meters per second] there is 1 m/s [50% of 2 m/s] to 7.5 m/s [ 150% of 5m/s] maximum deviation. By flow direction 25 is meant that starting from the flow (vertical inflow direction) which impinges perpendicularly on at least one separating chassis 23, the deviation range with respect to this vertical inflow direction is at most 180°, preferably 120°, particularly preferably 72°, Even only 45° and particularly preferably at most 20° are preferred. In this respect, it is assumed that the deviations are distributed symmetrically with respect to the vertical inflow direction.

The flow rectifier 64 is preferably designed flat and is positioned and/or fixed in the inner region 5 of the column 1 substantially parallel to the at least one separating tray 23 . The flow rectifier 64 is preferably at least partially made of a corrosion-resistant and high-temperature-resistant material and is fluid-permeable, for which purpose holes are provided in particular, which influence, on the one hand, the flow pattern especially with regard to speed and/or direction, however, On the other hand, to prevent clogging or closure of the pores, the flow straightener 64 preferably extends over the entire inner region 5 of the column 1 .

The flow straightener 64 thus comprises at least one of the following elements: at least one grid structure 67 , at least one honeycomb structure 68 , at least one perforated plate 69 or a so-called stack. These elements can therein be directly or indirectly connected to the separation chassis 23 , in particular form part of the separation chassis 23 . The lattice structure 67 comprises a plurality of elongated fibrous structures, which are connected to each other in a random manner or like a fabric, for example, coated metal wires are suitable as such elongated fibrous structures, and the honeycomb structure 68 can be Made as one-piece or multi-piece. The embodiment shown here comprises a plurality of smooth construction plies connected to form a honeycomb structure 68 . The orifice plate 69 can also be designed as a rectangle, an ellipse, a polygon or other forms except the circular embodiment shown, and the number of holes is preferably greater than 30% of the total area of the orifice plate 69 .

FIG. 6 shows a detail of an embodiment of a separation chassis 23 comprising a bottom plate 29 with a coating 22 which has less adhesion properties for liquids than steel. It can be seen from the illustration that coating 22 can be described with the aid of characteristic values layer thickness 71 , surface roughness 72 and porosity 73 . A coating 22, preferably comprising polytetrafluoroethylene, is applied to the contact surface 70, which would otherwise be in direct contact with the polymerizable substance. Sedimentation and polymerization of substances are thereby prevented.

Fig. 7 schematically shows an apparatus for producing acrylic acid. The plant has a first gas-phase oxidation reactor 76 for oxidizing propylene to acrolein, which is connected to another gas-phase oxidation reactor 77, in which acrolein is further oxidized to acrylic acid, then in another The acrylic acid gas mixture obtained in the reactor 77 is fed to a quenching device 78 which is connected indirectly or directly to the column 1 according to the invention. One or several other purification units 79 can be connected to the column of the invention. These purification units include, inter alia, crystallization devices, such as layered crystallizers, suspension crystallizers connected to a washing column, or also extractors or azeotropic mixed stills. The withdrawal unit 79 is preferably arranged on the part of the column 1 where acrylic acid of the highest purity is produced, here preferably the top 80 of the column. Acrylic acid of very high purity - mostly over 99.8% - is obtained by this configuration of the acrylic acid manufacturing plant. Devices of similar structure are also contemplated for other polymerizable substances than acrylic acid.

Fig. 8 schematically shows the structure of a test device for determining the density distribution of gas phase substances. The container 2 and the first separation chassis 23 are shown in dashed lines. An imaginary plane 81 below the separation chassis 23 is indicated by a section 85 in which the isotropic density distribution of the gaseous substances is determined. element. A radiation source 82 and a corresponding detector 83 for determining the amount of impinging radiation are arranged in the region of the plane 81 facing one another. The source 82 emits a beam through a center point 87 of a plane 81 , which corresponds substantially to the cross-section of the container 2 . Furthermore, another position of the source and detector is shown in dashed lines and indicated by (II). Positions (I) and (II) are occupied sequentially in time and are offset relative to each other with a change of direction 86 . In this case, a measurement step is carried out in each case. Detectors 83 then record the impinging pulsed radiation in each case.

The measurement results are shown schematically in FIG. 8 by two histograms, the measurements being carried out over a predetermined period of time and with a certain beam width 88 . The detectors 83 each generate an image showing the distribution of the count pulses (n) over the beam width 88 . The maximum values of the first measurement (position I) and the second measurement (position II) are denoted n _I and n _II in the figure. The integrals of the count pulses (n) over the beam width 88 are denoted by A _I and A _II , respectively. The value or shape of the corresponding integration or counting pulse value is here characteristic for the density of the medium penetrated by the beam or the gas phase substance transmitted. Larger values of the integral columnar form or count pulses show that the radiation emitted by the source 82 reaches the detector 83 for the most part. Conversely, very small count pulses or a sharply shaped image indicate a dense medium through which at least some of the radioactive rays do not penetrate.

If this measurement is carried out at several positions (I, II...) in the device described above, especially in the device according to the invention, then the isotropic The maximum deviation of the density is at most 15%, which means, for the exemplary embodiment shown, that the value of n _I is at least 70% of n _II . Since the number of detected pulses is characteristic of the density of the gas phase material penetrated by the beam, this characteristic value can be used as a measure of the density. Therefore, that is, it can be confirmed that an isotropic density distribution exists according to the present invention.

FIG. 9 schematically shows details of the concrete structure of a corrugated bottom plate 29 of a separate chassis 23 . In particular, such a bottom plate 29 has a plurality of holes 30 and is particularly advantageous in combination with the embodiments described here or independently of one another. The corrugated bottom plate 29 has the advantage that the droplets 26 adhering to the bottom surface are directed downwards The flow reaches troughs 90 and locally mixes with one another there, which further reduces the risk of polymerization. At the same time, this accumulation of fluid causes them to eventually fall off as well. An attachment 31 such as that shown in FIGS. 2 and 3 can be dispensed with if the bottom plate 29 is corrugated, since the corrugated shape itself provides a separation which prevents undesired back and forth flow of liquid. Preferably, several or even all separation bases 23 of the column 1 are provided with such a corrugated base plate 29 . Preferably, adjacently located base plates 29 are arranged offset relative to each other in the orientation and/or orientation direction of the corrugation shape, in particular in such a way that the crests 89 or troughs 90 of the base plates 29 each form an angle of approximately 90°.

Particular preference is given to a structure with a base plate 29 having a wave height 92 in the range from 0.5 to 5.0 cm, in particular from 1.2 to 1.7 cm. In this case, wave height 92 refers to the average vertical distance of peaks 89 and troughs 90 from one another. Here the horizontal spacing (corresponding to the wavelength 91 ) between the peak 89 and its adjacent trough 90 is about 3.0 cm to 10 cm, in particular, the wavelength 91 is in the range of 4.0 cm to 6.0 cm.

A further improvement in terms of reducing the polymerization tendency can be achieved by a special structure of the surfaces of the column 1 which come into contact with the polymerizable substances. This is especially the case for at least a part of the separation chassis 23 , the flow distributor 20 , the inlet pipe 4 , the flow straightener 64 or the container 2 .

According to a variant, at least one of the aforementioned surfaces or its coating has at least locally a particularly small average roughness (R _a ), the average roughness value being the absolute distance 96 of the actual profile (position) 94 from the intermediate position 93 Arithmetic mean of values (over benchmark span 95). The average roughness value here is preferably in the range of less than 2.0 µm (micrometer), especially in the range of 0.5 µm to 1.0 µm. This average roughness value reduces the tendency of the liquid to adhere to the surface it wets, causing the liquid to dribble or drip more quickly. Such an average roughness value is shown schematically by way of example in FIG. 9 with respect to the surface of the bottom plate 29 .

Furthermore, there is the possibility (alternatively or additionally) that at least one of the aforementioned regions is at least partially provided with a so-called self-cleaning surface or coating. Preferably, such a self-cleaning surface has an artificial, at least partially hydrophobic surface structure consisting of elevations and depressions, wherein the elevations and depressions are formed by particles fixed to the surface by means of a substrate. It is preferably characterized in that the particles have an uneven structure with protrusions and depressions in the nanometer range (nanostructures 97 are schematically represented in FIG. 9 ). Preferably, the protrusions have an average height of 20 to 500 nm (nanometers), particularly preferably 50 to 200 nm, and the distance between protrusions and depressions on the particles is preferably less than 500 nm, very particularly preferably less than 200 nm. Uneven structures with protrusions and/or depressions in the nanometer range can be formed, for example, by cavities, pores, scratches, peaks and/or points. The particles themselves have an average size of less than 50 μm (micrometer), especially less than 30 μm, very particularly preferably less than 20 μm, the particles preferably have a BET surface of 50 to 600 m ² /g (square meter per gram), the particles very particularly preferably have a BET surface of 50 to 200 m ² /g BET surface, the so-called "BET surface" refers to the specific surface area determined by the known BRUNAUER, EMMET and TELLER methods.

Different compounds from various fields of chemistry can be employed as structure-forming particles. Inorganic particles are preferably used here, preferably the particles have at least one material selected from the group consisting of silicates, silicates with additives, minerals, metal oxides, silicic acid, polymers and metal powders coated with silicic acid. Very particularly preferably, the particles have pyrogenic silicic acid or precipitated silicic acid, particularly preferably with a particle size of 1 μm (micrometer) are oxysilica, Al ₂ O ₃ , SiO ₂ , TiO ₂ , ZrO ₂ , gas-coated Zinc powder of sol R974, or polymers including powdered form, such as low-temperature, ground or spray-dried polytetrafluoroethylene (PTFE) or perfluorinated copolymers or corresponding copolymers with tetrafluoroethylene, such Particles or coatings for producing self-cleaning surfaces are available, for example, from the company DEGUSSA AG.

Measurement methods

The isotropic concentric density ("direction-dependent" density distribution) or deviation of the gas phase substance is determined, for example, by the method of the company Ingenieurbüro Bulander & Esper GmbH in Zwingenberg, Germany, wherein a directional beam is emitted to the detector by means of a radioactive source (with e.g. 5cm predetermined width). Where the source and detector are located on opposite sides of the tower so that the rays extend substantially horizontally and pass through the tower, for example cobalt (Co60) and cesium (Cs137) with an activity of 0.3 to 3.7 GBq are used as radioactive sources.

The radiation emitted during operation of the tower is preferably measured with a scintillation detector in the form of pulses per unit time (number) and fed to a processing and display device. In principle, it is also possible to arrange multiple detectors and sources, optionally arranged around the circumference of the tower, the latter arrangement having the advantage that the same values can be kept for comparison measurements in different directions. Experimental configuration, just using different sources and detectors, thus avoiding measurement errors due to incorrect installation.

For the structure of the test device, refer to the description of Fig. 8 for supplement.

During the emission of this radioactive beam through the gaseous matter for a predetermined period of time, a counter in the detector identifies the impinging rays and registers the pulses, the number of pulses per unit time being a measure of the density of the matter located between the source and the detector . Higher values indicate less density, since most of the emitted radiation reaches the detector, and correspondingly lower count pulse values indicate greater density.

For example, if the liquid and gaseous components are evenly distributed in a cross-section, then it can be known that the gaseous material flows uniformly, from which it can be seen that the separation chassis is partially blocked (so there is only a small amount of liquid components in the gaseous material, The density is therefore less) or eg there are regions of less gas flow (where the flow increases due to the reduced back pressure and thus an increase in density can be noticed).

In order to determine the isotropy, it is now proposed that first a measurement is made in a plane below the first separating chassis in a first direction and the radiation (n) detected within a predetermined time period (t; eg 5 minutes) is recorded. In order to reduce the effect of fluctuations in the operation of the column, this measurement can be carried out several times, wherein a value (n _i ) is measured in each time period (t), and then an average value (N) is formed and used as an isotropic benchmark. It should be added to this that the radiation beam is emitted with a width (for example 5 cm) and the detector optionally has such a resolution that the measured values over this width can be differentiated. The mean value or the area under the image (integral) can thus also be used as a basis for expressing the pulse rate (impulsrate) over this width.

After the eigenvalues or eigenintegrals of the detected rays have been determined, the above-mentioned procedure is repeated in the same plane but in a direction different from this, the angle between these two directions is preferably greater than 30°, in particular even greater than 40° . In this way, at least 2, in particular even at least 3 such measurements are performed from different directions.

In principle, the direction along the diameter of the tower should be chosen in order to ensure that the free rays passing through the gas phase material are of equal length, so that the detected rays can be compared with each other. This is possible because the beams pass through the same volume of gaseous matter, but it is of course also possible to choose a different beam path than this, but it should be ensured that the beam paths have the same length for each measurement.

In principle, the plane can be arranged arbitrarily within the column and is preferably arranged essentially parallel to the at least one separating tray. In order to test the uniformity of the flow, this directional beam can be carried out through the separation chassis, distillate or gas phase substances. In order to reflect the inflow characteristics of the first separation chassis, the plane should preferably be selected within the range of less than 200mm below the first separation chassis . In particular the plane is located in the range of 100 mm to 10 mm below the first separating chassis.

Within the meaning of the invention, in particular if the measured values (n and/or N) deviate by a maximum of 15%, then there is an isotropic density, in order to determine the deviation, the arithmetic mean of the measured values ( M). For a given number (X) of orientation measurements, it is defined as the quotient of the sum of measurements (n _x and/or N _x ) for each direction and the number of measurements (X). A maximum deviation of eg 5% means that the maximum measured value and the minimum measured value of the pulse rate are in the range of 0.95M to 1.05M. The deviations specified here preferably already take into account measurement deviations due to the cosmic background radiation (about +/−50 count pulses for a typical measurement time of 3 seconds and a measurement width of about 50 mm).

Fig. 10 schematically shows another embodiment of the inlet pipe 4 with a flow mixer 98 as a flow controller of a special structure in a perspective view, the shown inlet pipe 4 has a bend 99 in which the polymerizable substance Turning inside, if the polymerizable substance flows freely through this inlet pipe 4 without passing through the flow controller, then due to the bend 99, an inhomogeneous flow velocity distribution will be caused on the cross-section of the inlet pipe 4, which is due to the Flow turbulence and backflow. In order to avoid this phenomenon, a flow mixer 98 can also be provided upstream in the vicinity of the bend 99 (preferably immediately in front of it). Such a flow mixer 98 divides the incoming polymerizable substance into a plurality of filaments 100 and deflects the filaments in such a way that they pass through the bend 99 on substantially the same path, at which point the polymerizable substance is preferably at least locally produced. Rotation so that a consistent flow can be produced without fluctuations and backflow mixing, so that even flow across the cross-section of the inlet pipe 4 is also possible behind the bend 99 and a uniform flow of the polymerizable material distribution onto eg the flow distributor 20 . Finally, it should also be pointed out that such flow controllers and/or flow mixers 98 can be provided at several bends 99 of the feed line 4 .

Fig. 11 shows a partial sectional view of a container 2 with a spray device 101, wherein Fig. 12 shows a top view of the spray device 101 shown in Fig. during operation of tower 1). If the container has several separating trays 23 arranged one above the other, such a spraying device 101 is preferably used at least for the lowermost separating tray 23 of the container 2 . Liquid with polymerizable substances of a specific composition flows through this separation tray 23 , and the liquid is then collected in a collecting reservoir 24 , for example of container 2 . It is now advantageously provided that these liquids are supplied via the supply device 104 of the spray device 101 for cleaning the bottom surface of the separating tray 23 . Utilizing this liquid has the advantage that the distillation at the lowermost separation tray 23 is not significantly affected, and with this injection device 101, the components of the polymerizable substance attached to the bottom surface 105 of the separation tray 23 ( sometimes already partially aggregated) are effectively removed.

The spray device 101 itself can have a plurality of nozzles 102 which are designed in such a way that the separating tray 23 can be cleaned substantially uniformly over the entire cross section of the separating tray 23 . In this case, the arrangement and/or type of nozzles can be selected accordingly. FIG. 12 schematically shows a possible embodiment of a spraying device 101 with uniformly distributed nozzles 102 having substantially identical spraying zones 103 . A spraying device 101 of this construction is technically and economically simple, although this is not absolutely required. Here the nozzles are arranged such that the injection zones 103 do not substantially overlap, but this is also not mandatory. As nozzle 102 both a simple hole in the injection device 101 and (preferably) a separate nozzle component are conceivable.

Table of reference signs

1 tower 2 containers 3 connectors 4 input pipe 5 inner areas 6 outer surface 7 segments 8 bottom 9 divisions 10 coats 11 floors 12 inner surface 13 entrance 14 exit

15 flow controller 16 deflector 17 channels 18 segments 19 central axis 20 flow dispenser 21 tip 22 coats 23 separate chassis 24 collection reservoir 25 direction of flow 26 droplets 27 heater 28 pumps 29 bottom plate 30 holes 31 attachments 32 groups 33 openings 34 height 35 bars 36 length 37 rungs 38 spacers 39 width 40 yuan 41 cover plate 42 pitch 43 supports 44 supports 45 sides 46 size 47 concave 48 extension length 49 feet 50 size 51 distance 52 width 53 protrusions 54 arrows 55 gravity 56 liquid layers 57 steam bubble layer 58 droplet layers 59 bubbles 60 liquid

61 guide surface 62 central axis 63 outer edge 64 flow rectifier 65 connecting elements 66 shell surface 67 grid structure 68 honeycomb structure 69-well plate 70 contact surface 71 layers thick 72 surface roughness 73 Porosity 74 distance 75 liquid level 76 The first gas phase oxidation reactor 77 Another gas phase oxidation reactor 78 quenching device 79 purification unit 80 tower top 81 plane 82 sources 83 detectors 84 paths Section 85 86 direction change 87 center points 88 beam width 89 crests 90 trough 91 wavelengths 92 waves high 93 middle position 94 Actual Profiles 95 datum span 96 distance 97nm structure 98 flow mixer 99 bends 100 wire 101 Injection device 102 nozzles 103 spray area 104 supply device

Claims (22)

1. A separation chassis (23) for a distillation column (1) of polymerizable substances, comprising at least one bottom plate (29) with a plurality of holes (30) and at least one accessory (31), wherein said The attachment (31) divides the plurality of holes (30) into groups (32), and forms a fluid flow passage (33) through the at least one attachment (31), characterized in that the at least one attachment (31) dividing the base plate (29) into blocks (40), each block having a set (32) of holes (30), wherein the blocks (40) have an area in the range of ^1.2m2 to ^0.3m2 . 2 . The separating chassis ( 23 ) according to claim 1 , characterized in that the channel ( 33 ) extends from the base plate ( 29 ) over a height ( 34 ) of 1 mm to 100 mm. 3 . 3. The separating chassis (23) according to claim 1 or 2, characterized in that said at least one appendage (31 ) comprises at least one straight rib (35). 4. The separation chassis (23) according to claim 3, characterized in that, the separation chassis has at least one of the following configurations: (a) multiple attachments (31) are provided with a rib (35); (b) One attachment (31) is provided with a plurality of ribs (35). 5. The separating chassis (23) according to claim 4, said plurality of ribs being coupled to each other. 6. The separation chassis (23) according to claim 4, characterized in that, said at least one straight rib (35) has a length (36), and said plurality of passages (30) are at least partially formed by the following elements At least one qualification: (a) at least one crosspiece (37), which is part of said rib (35); (b) at least one spacer (38), which is a separate part, wherein these elements have a width (39), the sum of the widths (39) of these elements is less than the length (26) of said rib (35) ) of 80%. 7. The separation chassis (23) according to claim 1 or 2, characterized in that, the separation chassis has a cover plate (41), wherein the cover plate is arranged at 60mm to 200mm from the bottom plate (29). spacing (42), and also has a plurality of holes (30). 8. The separation chassis (23) according to claim 1 or 2, characterized in that, the separation chassis comprises a support (43), wherein the support (43) has at least one solid support (44) , the seat is in contact with the side (45) of the base plate (29) facing away from the at least one attachment (31) over a dimension (46) in the range of 200 mm to 1000 mm. 9. The separating chassis (23) according to claim 8, characterized in that said at least one support (44) has at least one recess (47) with an extension length (48) in the vicinity of said base plate (29) , wherein the sum of said extension lengths (48) is at least in the range of 80% to 30% of said dimension (46). 10. The separating chassis (23) according to claim 9, characterized in that said at least one support (44) is designed in a T-shape, wherein said at least one recess (47) is arranged substantially perpendicular to said On the support part of the base plate (29). 11. The separation chassis (23) according to claim 10, characterized in that said at least one T-shaped support (44) has a foot arranged parallel to said bottom plate (29) with a size of 50 mm to 100 mm part (49), wherein said at least one recess (47) is arranged at a distance (51) of less than 3 mm from said foot (49). 12. The separating chassis (23) according to claim 11, characterized in that said at least one recess (47) is directly connected to said foot (49). 13. The separating chassis (23) according to claim 11, characterized in that said at least one recess (47) has a width (52) of 40 mm to 120 mm. 14. The separating chassis (23) according to claim 8 or 9, characterized in that the at least one support (44) and the at least one attachment (31) are arranged perpendicularly to each other. 15. The separating chassis (23) according to claim 1 or 2, characterized in that it is at least partially coated with a coating (22) which has better sliding properties for liquids than steel. 16. A process for purifying polymerizable substances, wherein the polymerizable substances are fed as liquid substances via an inlet line (4) to a distillation unit with at least one separating tray (23) as claimed in any one of claims 1 to 15 in the column (1) and is transformed into gas phase substances in the inner zone (5). 17. The method according to claim 16, characterized in that, the gas phase material flows to a first separation chassis (23) arranged above the input pipe (4) with an isotropic density, wherein at the input The maximum deviation from the mean value of the isotropic density in a plane between the tube ( 4 ) and the first separating plate ( 23 ) is at most 15%. 18. The method of claim 16 or 17, wherein the polymerizable substance is (meth)acrylic acid. 19. A method according to claim 16 or 17, characterized in that there is a negative pressure in the inner region. 20. A method according to claim 16 or 17, characterized in that the liquid substance is superheated. 21. Process for the manufacture of polymerizable substances, wherein the polymerizable substance is synthesized in a reactor from at least one educt, which is subsequently subjected to the method for purifying the polymerizable substance according to any one of claims 16 to 20 Methods of polymerizing substances. 22. Use of a separating tray (23) according to any one of claims 1 to 15 for the distillation of polymerizable substances.

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